1. Field of the Invention
The present invention is in the field of loud speaker systems and particularly relates to a stereo speaker system which is especially well adapted for mounting at the back of a seat to enhance clarity and stereo separation of a conventional stereophonic or quadraphonic system.
2. The Prior Art
It has long been known in the art that a unique synergistic effect results when two loud speakers are used to reproduce the sounds picked up respectively by two separated microphones. The listener is subjected to the illusion that the reproduced sound is originating at various points around him. Recently it has become known that this effect can be enhanced by the use of four rather than two sound channels to produce a so-called quadraphonic sound.
It is well known that loud speakers can be mounted in a wide variety of locations. U.S. Pat. No. 3,230,320 to Kerr shows a speaker mounted on each side of the head rest of a dental chair. U.S. Pat. No. 3,237,713 to Leslie shows two speakers mounted on opposite sides within a helmet-like acoustical chamber for providing individualized instructions to a student in a classroom. In U.S. Pat. No. 2,541,980, Antone shows a single loud speaker mounted to a hair dryer. All three of these inventions tend to limit the sideward vision of the listener and to limit his ability to move about.
A number of inventions have placed speakers in vehicles for various purposes. U.S. Pat. No. 1,997,408 to Holmes shows a single speaker attachable to the back of a seat on its front surface at one side and positionable vertically relative to the listener's ear. U.S. Pat. No. 3,158,835 shows speakers mounted on the inside of a car closest to the operator's left ear and on the interior top of the car an equal distance from the operator's right ear for use in a safety device to permit the driver to sense the sounds outside the automobile. U.S. Pat. No. 2,908,766 to Taylor shows a pair of speakers mounted on the front side of a seat back on the left and right sides of a passenger's head. These three inventions all have in common the disadvantage that the passenger's sideward vision is obscured by the speakers, and in the event the vehicle lurches sidewardly, the passenger's head will be thrown against the speakers.
An alternative to speakers is the use of head phones. Unfortunately, head phones are not comfortable to wear for long periods of time, and they restrict the ability of the listener to move about freely. Certain types of head phones interfere with the listener's coiffure. When used in a vehicle, head phones are definitely a hazard because they shut out all outside sounds, whether or not the head phones are in operation.
Thus the need can be seen for a stereo speaker system which does not obscure the listener's vision, which does not restrain his freedom of movement, and which, when mounted in a vehicle, will not shut out all outside sounds and which will not present a safety hazard to the listener in the event of a crash.
Commercially, it is highly desirable that the stereo speaker system include means for mounting it to a portion of the vehicle in which it is to be used. Because of the great variety of vehicle shapes and styles, the mounting means must be extremely versatile and must be capable of securing the speaker system to the chosen portion of the vehicle to prevent the speakers from coming loose and presenting a safety hazard.